On a Method of Expressing by Signs the Action of Machinery

C ^50 3

iCVUL On a method of expressing by signs the action of
machinery^ By Charles Babbage, Esq. F. R. S. Com--
municatedJamary 17, 1826,

Read March 16, 1826.

XN the construction of an engine, on which I have now been
for some time occupied, for the purpose of calculating tables
and impressing the results on plates of copper, I experienced
great delay and inconvenience from the difficulty of ascertain-
ing from the drawings the state of motion or rest of any
individual part at any given instant of time : and if it became
necessary to enquire into the state of several parts at the
same moment the labour was much encreased.

In the description of machinery by means of drawings, it
is only possible to represent an engine in one particular state
of its action. If indeed it is very simple in its operations, a
succession of drawings may be made of it in each state of its
progress which will represent its whole course; but this
rarely happens, and is attended with the inconvenience and
expence of numerous drawings. The difficulty of retaining
in the mind all the cotemporaneous and successive move-
ments of a complicated machine, and the still greater difficulty
of properly timing movements which had already been pro-
vided for, induced me to seek for some method by which I
might at a glance of the eye select any particular part, and
find at any given time its state of motion or rest, its relation
to the motions of any other part of the machine,, and if

Mr. Babbage on a method of expressing^ &c. 251

necessary trace back the sources of its movement through
all its successive stages to the original moving povv^er. I
soon felt that the forms of ordinary language were far too
diffuse to admit of any expectation of removing the difficulty,
and being convinced from experience of the vast power
which analysis derives from the great condensation of mean«
ing in the language it employs, I was not long in deciding
that the most favourable path to pursue was to have recourse
to the language of signs. It then became necessary to con-
trive a notation which ought if possible to be at once simple
and expressive, easily understood at the commencement,
fid capable of being readily retained in the memory from
the proper adaptation of the signs to the circujnstances they
were intended to represent. The first thing to be done was
obviously to make an accurate enumeration of all the moving
parts, and to appropriate a name to each ; the multitude of
different contrivances in various machinery, precluded all
idea of substituting signs for these parts. They were there-
fore written down in succession, only observing to preserve
such an order that those which jointly concur for accom-
plishing the effect of any separate part of the machine might
be found situated near to each other: thus in a clock, those
parts which belong to the striking part ought to be placed
together, whilst those by which the repeating part operates
ought, although kept distinct, yet to be as a whole, adjacent
to the former part.

Each of these names is attached to a faint line which runs
longitudinally down the page, and which may for the sake
of reference be called its indicating line.

The next object was to connect the notation with the

2^2 Mr. Babbage on a method of expressing

drawings of the machine, in order that the two might mu-
tually illustrate and explain each other.

It is convenient in the three representations of a machine,
to employ the same letters for each part ; in order to connect
these with the notations, the letters which in the several
drawings refer to the same parts, are placed upon the in-
dicating lines immediately under the names of the things.
If circumstances should prevent us from adhering to this
rule, it would be desirable to mark those things represented
in the plan by the ordinary letters of the alphabet, those
pointed out for one of the other projections by the letters of
an accented alphabet, and the parts delineated on the th^v 1
projection by a doubly accented alphabet. In engines of so
complicated a nature as to require sections at various parts
as w^ell as the three projections, this system is equally ap-
plicable, and its advantage consists in this — that the number
of accents on the letter indicates at once the number of
the drawing on which it appears, and when it is intended to
refer to several at the same time, the requisite letters may
be employed and placed in the order in which the drawings
will best illustrate the part under examination.

The next circumstance which can be indicated by the
system of mechanical notation which I propose, more readily
than by drawings, is the number of teeth on each wheel or
sector, or the number of pins or studs on any revolving
barrel. A line immediately succeeding that which contains
the references to the drawings is devoted to this purpose,
and on each vertical line indicating any particular part of the
machine, is written the number of teeth belonging to it. As
there is generally a great variety of parts of machinery wMcjIi

by signs the action of machinery . 253

do not consist of teeth ; of course every vertical line will not
have a number attached to it.

The three lines immediately succeeding this, are devoted
to the indication of the velocities of the several parts of the
machine. The first must have, on the indicating line of all
those parts which have a rectilinear motion, numbers ex-
pressing the velocity with which those parts move, and if
this velocity is variable, two numbers should be written, one
expressing the greatest, the other the least velocity of the
part. The second line must have numbers expressing the
angular velocity of all those parts which revolve ; the time
of 1 evoluion of some one of them being taken as the unit of
the measure of angular velocity.

It sometimes happens that two wheels have the same
angular velocity when they move ; but from the structure of
the machine, one of them rests one half of the time during
which the other is in action. In this case, although their
angular velocities are equal, their comparative velocities are
as 1 to 2 ; for the second wheel makes two revolutions, whilst
the other only makes one, A line is devoted to the numbers
which thus arise, and it is entitled. Comparative Angular
Velocity.

The next object to be considered is the course through
which the moving power is transmitted, and the particular
modes by which each part derives its movement from that
immediately preceding it in the order of action. The sign
which I have chosen to indicate this transmission of motion
(an arrow), is one very generally employed to denote the
direction of motion in mechanical drawings ; it will therefore
readily suggest the direction in which the movement is
transmitted. There are however various ways by which

MDCCCXXVI. LI

B54

Mr, Babbage on a method of expressing

motion is communicated ; and it becomes a matter of some
importance to consider whether, without interfering with the
sign just selected, some modification might not be intro-
duced into its minor parts, which, leaving it unaltered in the
general form, should yet indicate the peculiar nature of the
means by which the movement is accomplished.

On enumerating those modes in which motion is usually
communicated, it appeared that they may be reduced to the
following.

One piece may recei\re its

This may be indicated by an
arrow with a bar at the end.

motion from another by being
permanently attached to it as a
pin on a wheel, or a wheel and
pinion on the same axis.

One piece may be driven by
another in such a manner that

when the driver moves, the other \^j^^ ^^^ow without any bar.
also always moves; as happens
when a wheel is driven by a
pinion.

^

One thing may be attached to
another by stiff friction.

.#■

One piece may be driven by
another, and yet not always move
when the latter moves ; as is the
case when a stud lifts a bolt once
in the course of its revolution.

One wheel may be connected
with another by a ratchet, as the
great wheel of a clock is attached
to the fusee.

An arrow formed of a line in-
terrupted by dots.

By an arrow, the first half of
which is a full line, and the
second half a dotted one.

•«»•• t ••••i

Byadotted arrowwith a ratchet
tooth at its end.

hy signs the action of machinery . 255

Each of the vertical lines, representing any part of the ma-
chine, must now be connected with that representing the
part from which it receives its movement, by an arrow of
such a kind as the preceding table indicates ; and if any part
derives motion from two or more sources, it must be con-
nected by the proper arrows with each origin of its move-
ment. It will in some cases contribute to the better under-
standing of the machine, if those parts which derive move-
ment from two or more sources have their names connected
by a bracket, with two or more vertical lines, which may be
employed to indicate the different motions separately. Thus
if a shaft has a circular as well as a longitudinal motion, the
two lines attached to its name should be characterised by a
distinguishing mark, such as (vert, motion) and (circ. motion).
Whenever any two or more motions take place at the same
time, this is essential ; aiid when they do not, it is convenient
for the purpose of distinguishing them.

All machines require, after their parts are finished and put
together, certain alterations which are called adjustments.
Some of these are permanent, and, when once fixed by the
maker, require no further care. Others depend on the nature
of the work they are intended to perform, as in the instance
of a corn mill ; the distance between the stones is altered
according to the fineness of the flour to be ground : these
may be called usual adjustments ; whilst there are others
depending on the winding up of a weight, or spring, which
may be called periodic adjustments. As it is very desirable
to know all the adjustments of a machine, a space is reserved,
below that in which the connections of the moving parts are
exhibited, where these n.ay be indicated ; if there are many

ss6 Mr. Babbage on a method of expressing

adjustments, this space may be subdivided into three, and
appropriated to each of the three species just enumerated, the
permanent, the usual, and the periodic: if their number is
small, it is better merely to distinguish them by a modifica-
tion of their signs. It is sometimes impossible to perforni
such adjustment, except in a particular succession ; and it is
always convenient to adhere to one particular order. Num-
bers attached to their respective lines denote the order in
which the parts are to be adjusted ; and as it will sometimes
happen that two or more adjustments must be made at the
same time, in that case the same numbers must be written on
the lines belonging to all those parts which it is necessary to
adjust simultaneously.

If it is convenient to distinguish between the species of
adjustments without separating them by hnes, this may be
accomplished by putting a line above or below the figures,
or inclosing them in a circle, or by some similar mode. I
have attached the letter P to those which are periodic.

It would add to the knowlege thus conveyed, if the sign
indicating adjustment also gave us some information respect-
ing its nature ; there are, however, so many different species,
that it is perhaps better in the first instance to confine our-
selves to a few of the most common, and to leave to those
whom may have occasion to employ this kind of notation,
the contrivance of signs, fitted for their more immediate

purpose.

One of the most common adjustments is that of deter-
mining the distance between two parts, as between the point
of suspension and the centre of oscillation of a pendulum.
This might be indicated by a small line crossing the vertical

by signs the action of machinery.

S57

line attached to the part.

If the distance between two

parts, which are represented by different lines, is to be al-
tered, their lines may be connected by an horizontal line.

\

D

Thus the adjustment of A in the above figure depends on
its distance from D.

This adjustment often determines the length of a stroke, and
sometimes the eccentricity of an eccentric, which depends on
the linear distance between its centre and its centre of motion.

The next most frequently occurring adjustment is that
which is sometimes necessary in fixing two wheels, or a wheel
and an arm on the same axis. This relation of angular posi-
tion, may be indicated by a circle and two radii placed at
the requisite angle, or that angle may be stated in figures
and inclosed within the circle ; this circle ought however to
be connected by a line with the other part, with which the
angle is to be formed, thus,

A B C D E ¥

o

which means that an adjustment is to be made by fixing A on
its axis, making a right angle with D, and that F must also
make with C an angle of sixty degrees. In speaking of these
angles, it should always be observed that they refer to the
angles made by the parts on one of the planes of projection.

£58 Mr. Babbage on a method oj expressing

When it is thought requisite to enter into this minute detail
of adjustments, it will be necessary, in order to avoid con-
fusion, to put the lines indicating the order of adjustment,
above and distinct from these signs.

The last and most essential circumstance to be represented,
is the succession of the movements which take place in the
working of the machine. Almost all machinery, after a cer-
tain number of successive operations, recommences the same
Qourse which it had just completed, and the work which it
performs usually consists of a multitude of repetitions of the
same course of particular motions.

It is one of the great objects of the notation I am now ex-
plaining, to point out a method by which, at any instant of
time in this course or cycle of operations of any machine, we
may know the state of motion or rest of every particular
part ; to present a picture by which we may, on inspection,
see not only the motion at that moment of time, but the
whole history of its movements, as well as that of all the
cotemporaneous changes from the beginning of the cycle.

In order to accomplish this, each of the vertical indicating
lines representing any part of the machine, has, adjacent to
it, other lines drawn in the same direction : these accompa-
nying lines denote the state of motion or rest of the part to
which they refer, according to the following rules,

1. Unbroken lines indicate motion,

s. Lines on the right side indicate that the motion is
from right to left/

3- Lines on the left side indicate that the direction of
the motion is from left to right.

(

I

by signs the action of machinery. 359

4, If the movements are such as not to admit of this

distinGtion, then when lines are drawn adjacent
to an indicating hne, and on opposite sides of it,
they signify motions in opposite directions*

5. Parallel straight lines denote uniform motion.

( 6. Curved lines denote a variable velocity. It is con-
venient as far as possible to make the ordinates
of the curve proportional to the different veloci-
ties.

7. If the motion may be greater or less within certain

limits : then if the motion begin at a fixed mo-
ment of time, and it is uncertain when it will
terminate, the line denoting motion must extend
from one limit to the other, and must be con-
nected by a small cross line at its commence-
ment with the indicating line. If the beginning
of its motion is uncertain, but its end determined,
then the cross line must be at its termination.
If the commencement and the termination of any
motion are both uncertain, the line representing
motion must be connected with the indicating
line in the middle by a cross line.

8. Dotted lines imply rest. It is convenient some-

times to denote a state of rest by the absence of
any line whatever.

9. If the thing indicated be a click, bolt, or valve, its

dotted line should be on the right side if it is out
of action, unbolted, or open, and on the left side
if the reverse is the case.

I

I

1

I

i

I

260 Mr.. Babb AGE on a method of expressing

10, If a bolt may rest in three positions : ist, bolted on
the right side ; 2nd, unbolted ; srd, bolted on
the left side. When it is unbolted, and in the
middle station, use two lines whilst in the act of
unbolting, and two lines of dots, one on each side

'[ of, and close to the indicating line, whilst it rests

in this position. When it is bolted on the right
side, a line or a line of dots at a greater distance

• on the right hand from the indicating line will

represent it. And if it is bolted on the left, a
similar mode of denoting it must be used on that
side. Any explanation may, if required, be put
in words at the end of the notation, as will be
observed in that of the hydraulic ram, Plate IV.

I have now explained means of denoting by signs almost
all those circumstances which usually occur in the motion of
machinery : if other modifications of movement should pre-
sent themselves, it will not be difficult for any one who has
rendered himself familiar with the symbols employed in this
Paper, to contrive others adapted to the new combinations
which may present themselves.

The two machines which I have selected as illustrations of
the application of this method, are, the common eight day
clock, and the hydraulic ram. The former was made choice
of from its construction being very generally known, and
I was induced to choose the latter from the apparent difficulty
of applying this method to its operations.

The advantages which appear to result from the employ-
ment of this mechanical notation, are to render the description
pf machinery considerably shorter than it can be when ex-

by signs the action of machinery. 261

pressed in words. The signs, if they have been properly
chosen, and if they should be generally adopted, will form
as it were an universal language ; and to those who become
skilful in their use, they will supply the means of writing
down at sight even the most complicated machine, and of
understanding the order and succession of the movements of
any engine of which they possess the drawings and the me-
chanical notation. In contriving machinery, in which it is
necessary that numerous wheels and levers, deriving their
motion from distant parts of the engine, should concur at
some instant of time, or in some precise order, for the proper
performance of a particular operation, it furnishes most im-
portant assistance; and I have myself experienced the ad-
vantages of its application to my own calculating engine^
when all other methods appeared nearly hopeless,

DESCRIPTION OF THE PLATES.

Plates VII. and VIII. are different representations of an eight
day clock, for the purpose of comparing it with the notation.

Plate IX, represents the mechanical notation of the same
clock.

Under the names of each part follow the letters which
distinguish them in the plates.

The next line contains numbers which mark the number
of teeth in each wheel, pinion, or sector.

The following line is intended to contain numbers expres-
sing the linear velocity of the different parts : in the eight
day clock this line is vacant, because almost all the motions
are circular.

The next line indicates the angular velocity of each part ;
MDCccxxvi. Mm

m6^ Mr. Bmbwage on a method of ewpressing

and in order to render the velocity of the striking partS'
eomparaMe with those of the time part, I have supposed oile
reTolution of the striking fusee to be made in? one minute : I
have also taken one revolution of the scaperaent wheel, or
one minute of time as the unit of angular velocity.

The space entitled comparative angular velocity, expresses
the number of revolutions one wheel makes during one re-
volution of some other ; it differs from the real angular
velocity, because one wheel may Jbe at rest during part of
the time. Thus the clock strikes 78 strokes during twelve
hours, or one revolution of the hour hand : if this be called
unity, the pin wheel moves through 78 pins or sf revolutions
in the same time; its comparative angular velocity is there-
fore 9|.

The space in which the origin of motion is given, will not
require any explanation after reading the description of the
signs employed in this paper.

The adjuistraents are numbered in the order in which they
are to be made. No, 1, is attached to the crutch : the first
adjustment is to set the clock in beat. No. 2, is to adjust the
length of the pendulum to beat seconds. No. 3, occurs in
three different places, at the hour and minute hands, and at
the snail on the hour wheel. It is necessary that when the
hour hand is at a given figure, three o'clock for instance,
that the minute hand should be set to twelve o'clock ; it is
also necessary that the snail should be in such a position that
the clock may strike threeo These adjustments must be
made at the same time. No» 4, is for the adjustment of the
seconds hand to 60 seconds. No. 5, is double, and is for the
adjustment of the minute and hour hand to the next whole

\' F

7ul.Z>u/^. M\}Q^£:XMl.I'lul'e. . PTI.p. 26

>/

^.J^urve/l . scii//?f^

J^'AS^.Jh^^. MjyCCC^XVLJ'^;-^/^. imr.p. 2dl

Vi

^.J}/yr-reM. scz^4f^}

:e ][ u ;oi T I J ..1 Y" ■ o jl o c «

i^Zl/y^' /i±R3'

/i/iA/)mo OFF PARI'

S'T/^J7i:/jV(J PAR

Moti^fft

A^AMBS :

I

1

^<V^

Nij

^ ^

1 ^

^ ^

A

^
^

N)

N.

I

,1

1

c»

•S)

C5:

Si

is

1
I

N "^ 'N

^

"N
^

(•3 •>
. \

A

I

•I

^

V

Sj

I

NX)

I

1

I

"1

I

,.*<>■'

"-■r^

%
-a

s

\

'v

§■

V

§:

s

•^

•\

N\i

V

'N

>s

^^ ^ /

G-

y

I

& S

M

TJiE71N

fiO 3 60. $ e/i B P&

40 /fO d' 72

8 4t^ I ^ A

IJWEAR

VjiZfkyjy'Y

IWGIIAAR
YliLOaiTY

/ /

./y

o

J

/

4

J

/tf

op

/jO

72(>

720

/ / / / / I

/i\y 'oY> od 7iid Jo 7^0

72('> J<)

/

COMPS
'YeLOCJ'J'Y

ADJVS'T'
MEJS/TS

A

% . /. t

4-..00

63
64

M "

rr/

,. O

t

/

o

/,..

5

)

"I"

C (

s

p p

I

G 0,

1

i) P

1

C _..,C

'■ »'

;) )

C (:

t

,) 3

c

1

) .^

c c

1

5 .)

C: C

(

P .)

I

(r C-

1

5 ')

(,.(!._

1

J) 3

\

G_._ Q__

5 P

f

( C

1

)

)

( (

1

) ■

)

c c

1

) 5

I

(Q I

1

P P '

1

C (:■ .

1

J J :

1

Cj (: :

1

T D ^

1

(^ Q ;

1

j)

(1 (:

t

I i

I I

I I

I I

1
1

1

1
1

A

A

:

J

~A

I ; I

I t

"\\ ' T

"\\ V

\ w I j li i| I

I Ij l| I Ml

I II \' II I

M |i I I

i: I

I i I

I I

I i I I I

1

I

jl--'

'" i":

1

A

i"

1

1

^'" r

v
r

I

1

""'i

\

1 1

1

I i I

I ; i:

I I

M I I

I I

t 1

I ' I

M I II I 1^ I I

i; (i li 1 1 I t

I ! i I i

n I

I I

I I I I

\ M II l| I I I

ti II ti 1; I

ii I

H t i ) I

I I ; I ; I

h 1 1 II 11 I

i: II I i II \ I

II \ II i| II I

I 1 M 1; I

I I I III

I I

|; I

'"l; \

T" 1 1

j :

li ' I:

I I

li I I

I I

II I

I I I I I I

I i

V. I :

I ■ I

■kM4 sa?A ~'jm .'7<M .'70// c

ZVr? E4IiT..

f-Jty/Zt:/.

R£rjEATJJVG JMIiT

§:

1^

>s

N

.1

\

.1

.?^

N S ^

^^

I

•I

N

1

-Nj

I

.5i

.Si'
I

•^

'^^

-^

.>►

^

1

1

V

^>

.■^•'

\)

^

V

i"^
s

1

i

'J

1

1

^
'^
•^

^

t

N

1^

V

1

^

^

^

«a

^

i^

'^ / 3 /{S 8 0/i 8 a S4

J^

I I

.'W, .^ m S4 ./Or ^H' A>i / /

84

2

S8k

9.

.3

33i

ii-^.

^-— ; ^ H f< H

<~

7^

V-

i

!

\
1

;

-'--■

"'

1
___^^ i

i i I

\ \ \
I

'■■^ i _ __ i

: ; '■ i

/,..

5

f

7
8

I)

lO

II

J2

M

Iff

ft

17
19

Zl

22
23 \
2/f^
23

27

28
j 9^
\ 30

31

32

33

34'-
3^

f.

37
38

r n

i I ■

(j^X _ I,

( (

C i

) 5 ■'

I : 11 l| l| I I I i l| l| I

T 1 7 "11 """Ti I ; I I II M

I i I i I! I : I ! I

1!

jr--T

I: I

' i"l j

I I

1; I

I:

C

c

c
(
c
c
c
c
c
(
c
c
c
c

I

) I !

I I

i

li-

lt I

II I

II ■ I,

TV"" i ;

I

"i !"■"■■""■ I

i

1 I

\- I

' j

It "T

,. i _

'I I

"( \'" V

M" i li

M I

I; I

I ; I

II I ; M I

|! li I; I

I I

I I II h t

? i

I i t

Il t! li I

) I I

H I

_.J,.,. ., , L

I I t

i
'li "'""1"

1 " i

I I ; I ■ I

M < : II I

1 1 I

'ti""""'"'"'''

1

'j '■

I I

M li li I II I

\ h II li II I

I I li i

li I 1;

I t

1

1

I ; 1

1

\ li 1

1 1

T

1

T'" r

1

1 rj \

I'l

""1

""' T

j

i'j 1"

„ ^

1] 1I 1

1"

f-^-J

i'-

'"i'""""'Ti '" 1'"

\

" rj M " 1"

i ;

"i\ r

'T'i i'

I

f
!

"i] r
"li i"

1] "'"'" 1'

M I I 1; ii ""'V

'\' "" I'j '^"1] ""^li'"'"""i:

i I ! I

I'i ""'V' """1I "'^Ti i'

iT 'i\ Vi"""""\f"""\\

\ li I

I t

II I

li I

I I

I! I

11 I

li li I i I

I

I I

II

li I

II t

I i I

n t

1 I

!| I I

li I I

M 1

I I

1 I 1! I

i I

II I

I I

I I I I I I

I ' I r I i t : I : I

I I

Il li II I Ij I
li 1! " i'j " 'I'i "li^" \

'i' li" I ! 1 1 1'i' I

ij r i""i t"'| li i'

"i" :'"""""" t'i r '"\'\ J'f i'

i'i \\ \l I i" "1 i \ ,

I ! \\ 1 1 """"1 : \'> I

ii I il \

li M I i I : I

'\<" ""\^ i'l '" r-i I

1 1 \T " I '"" I i' " i

li I

I

I! Il li I

I I I

I I

II I I I I: I

i I ! i

'T'i "i| il I j 1":'" I

'li i'; I : I ;■ "■ " ii ■ ■■ I

I M I I

I I

li 1
I i I
il I

i'j I

1 1 1

It I

i : I

I I I

|i I

I

1

1

I I

I I

li I

t I I

I I

I I

I 1

I I

I I

I I

I I I

I I I

' i '

li" I

■|j I

I i "1

_1 Li

I \

\ ■•

\ I

, — _

: 1

I

\ _ i ___!_

t (

Jf . Tu/^reSl' . so.

I'Ml. Tm^ns. MDCCC^XJn:../'/a^. X.p.2ffl

£^ .Tuj'rell . so

by signs tke action of machinery. S63

minute to that which is indicated by the watch by which the
clock is set. No. 6, is for the pendulum, which must be held
aside at its extreme arc until the instant at which the watch
reaches the time set on the face of the clock ; it must then
be set free*

The remaining part of the notation indicates the action of
every part at all times ; but as the whole cycle of twelve
hours would occupy too much space, a portion only is given
about the hour of four : from this the machine may be suf-
ficiently understood. As an instance of its use, let lis enquire
what movements are taking place at seven seconds after four
o'clock. On looking down on the left hand side to the time
Just mentioned, we observe between the end of the sixths, and
end of the seventh second, that the pendulum and crutch
begin to move from the right to the left, increasing their
velocity to a maximum, and then diminishing it; that the
whole train of wheels of the time part are at rest during the
greater part of that second, and all move simultaneously a
little before its termination. The greater part of the train of
the striking part is moving uniformly; but two parts the
cross piece, and the other moving the hammer, being at the
commencement of this second in a state of motion from right
to left, suddenly have that motion reversed for a short time:
this is at the moment of striking: two other pieces, the
hawk's bill, and the gathering pallet^ appears to act at the
same moment.

If the course of movement of any one part is required
throughout the whole cycle of the machine's action, we have
only to follow its indicating line. If it is required to find
what motions take place at the same time, we have only to
took along the horizontal line marked by the time specified.

q64< Mr. Babbage on a method of expressing

Let us now enquire into the source of motion of the minute
hand. On looking down to the space in which the origin of
motion is given, we observe an arrow point, which conveys
us to the

Cannon pinion, with which it is connected permanently.

The cannon pinion is driven by the centre or hour wheels
with which it is connected by stiff friction.

The hour wheel is driven by its pinion, to which it is per-
manently attached.

The hour wheel pinion is driven by the great wheel, into
which it works.

The great wheel is driven by the fusee, with which it is
connected by a ratchet.

The fusee is driven by the spring barrel or main springs
which is the origin of all the movements.

When that part of the notation which relates to the suc-
cessive movements of the machine is of considerable extent^
it is convenient to write on a separate piece of paper the
names of every part, at the same distances from each other
as the indicating lines, and exactly as they are placed at the
top. By sliding this paper down the page to any part which
is under consideration, the trouble of continual reference to
the top of the drawing will be avoided.

Plate X. represents the hydraulic ram: its mechanical
notation is added below it.

A, is the supplying pipe.

B, is the great valve.

C, the valve into the air vesseL

D, the air vessel.

E, the ascending water.

F^ the small air valve ; — its office is to supply a small

by signs the action of machinery. 265

quantity of air at each stroke ; it opens when the valve C is^
just closed, and a regurgitation takes place in the supplying
pipe just previous to the opening of the great valve. Without
this contrivance, the pressure on the air in the air vessel
would cause it to be soon absorbed by the water, and the
engine would cease to act.

In this notation two indicating lines A, A, are allowed to
the supplying water, because it takes three different courses
during the action of the machine. The first of these marks
the time of its motion when it enters the air vessel, and the
second indicates its course when passing through the great
valve, and also its course when, owing to the elasticity of the
materials, its motion is for an instant reversed, at which
moment air is taken in at the air valve F.

The action of the machine is as follows : the supplying
water rushing along the great pipe passes out at the great
valve ; it acquires velocity until the pressure of the effluent
water against the under part of the great valve causes it to
close suddenly. At this moment the whole momentum of
the water is directed against the sides of the machine, and
the air valve being the weakest part gives way, and admits
a small quantity of water ; the air spring soon resists suf-
ficiently to close the air valve : at this moment the elasticity
of the apparatus re-acting on the water in the great pipe,
drives it back for an instant, during which the pressure of
the atmosphere opens the air valve, and a small quantity of
air enters ; this finds its way to the air chambers, which
easily discharges it through the ascending pipe if too mucli
air has entered.

fjijjlijiiiiii Ijjljj 111 jiiijill^ijilfiliiiif

1

u^"-'m

lltizz

J5

2^:

'It: